The main issues are using Structured{Serialize,Deserailize} instead of
Structured{Serialize,Deserialize}WithTransfer and the temporary
execution context usage for StructuredDeserialize.
Allows Discord to load once again, as it uses a postMessage scheduler
to render components, including the main App component. The callback
checked the (previously) non-existent source attribute of the
MessageEvent and returned if it was not the main window.
Fixes the Twitch cookie consent banner saying "failed integrity check"
for unknown reasons, but presumably related to the source and origin
attributes.
